SDL corrupting other X displays

I’m am having a problem running the SDL test apps on my system. I have an
unusual 3 head setup as follows:

  • Onboard Intel 915 chipset driving the primary and secondary displays using
    the Intel Embedded Graphics Driver.
  • nVidia PCI card driving a third display using the default X driver
  • A single X server handles all three displays.

If I try to run one of the SDL test apps such as testwin on any of the
displays, it will randomly corrupt one or more of the displays. Sometimes the
app runs and all of the displays remain unaffected but most of the time they
become corrupted.

Has anyone seen this before? Is there a way to prevent it?